Low-pressure mercury lamp having a spiral arc tube and method for assembling the same

ABSTRACT

An arc tube is formed by a glass tube that is turned at a substantially middle thereof and wound around a spiral axis from the middle, to have a double-spiral structure. End portions of the arc tub are wound around the spiral axis. A holder has insertion openings formed therein in such shapes that correspond to shapes of the ends of the arc tube. The insertion openings allow the ends of the arc tube to be inserted along a bottom wall of the holder. The holder also includes guide grooves provided in the areas before the insertion openings in the spiral direction of the ends of the arc tube. The guide grooves allow the end portions of the arc tube to come in contact, and when the arc tube is rotated around the axis, guide the ends of the arc tube to the insertion openings.

TECHNICAL FIELD

The present invention relates to a low-pressure mercury lamp thatincludes a holder holding an arc tube in a state where at least one endof the arc tube is inserted in an insertion opening formed in theholder, and a method for assembling the low-pressure mercury lamp.

BACKGROUND ART

In the present energy-saving era, a lot of efforts have been made todevelop low-pressure mercury lamps. In particular, fluorescent lamps,specifically compact self-ballasted fluorescent lamps that exhibit highluminous efficiency and long life, are calling attentions as lightsources alternative to incandescent lamps. As one example, compactself-ballasted fluorescent lamps may include double-spiral arc tubesformed so that end portions stand vertically and remaining portions arewound in a double spiral around the axis of spiral.

Compact self-ballasted fluorescent lamps including such double-spiralarc tubes have a higher total height than that of incandescent lamps.The problem therefore is that such a compact self-ballasted fluorescentlamp may partially protrude from an existing lighting fixture designedfor an incandescent lamp. To solve this problem, the inventors of thepresent application have come up with the idea that the total height ofcompact self-ballasted fluorescent lamps can be reduced by winding alsothe end portions of the arc tube, which had conventionally been formedto stand vertically, into a double spiral around the axis of spiral.With this idea, the inventors have succeeded in downsizing compactself-ballasted fluorescent lamps to substantially the same size asincandescent lamps.

FIG. 1 shows a holding member for holding an arc tube whose end portionsare formed in a double spiral. As shown in the figure, the holdingmember 906 is in a cylindrical shape whose one end is closed, and has,on its closed end, i.e., on its bottom wall 961, a pair of tubular partsin which a pair of insertion openings 963 and 964 are formed forallowing both ends of the arc tube to be inserted therethrough. Theholding member 906 holds the arc tube by bonding the ends of the arctube that have been inserted therein through the insertion openings 963and 964 to the inner surface of the holding member 906 via a bondingagent.

Although compact self-ballasted fluorescent lamps including theabove-described arc tube whose end portions are formed in a doublespiral can have a low total height substantially the same as that ofincandescent lamps, a problem still remains as that inserting the endsof the arc tube thorough the insertion openings 963 and 964 of theholding member 906 is extremely difficult. To be more specific, theinsertion of the ends of the arc tube is extremely difficult because theinsertion openings 963 and 964 are provided in directions opposite toeach other. Once one end of the arc tube is inserted through theinsertion opening 963, the other end of the arc tube goes off from theinsertion opening 964.

The insertion of the ends of the arc tube through the insertion openings963 and 964 can be made relatively easy by enlarging the insertionopenings 963 and 964. If the insertion openings 963 and 964 are large,however, another problem arises when the ends of the arc tube are bondedto the inner surface of the holding member 906 via a bonding agent. Theproblem is that the bonding member may flow out from the insertionopenings 963 and 964, thereby leading to serious degradation of theappearance.

DISCLOSURE OF THE INVENTION

In view of the above problems, the object of the present invention is toprovide a low-pressure mercury lamp in which ends of an arc tube can beeasily inserted into a holding member without for example enlarging theinsertion openings, and also to provide a method for assembling thelow-pressure mercury lamp.

The above object of the present invention can be achieved by alow-pressure mercury lamp, including: an arc tube whose at least one endis wound around an axis entirely in a longitudinal direction thereof;and a holding member that holds the arc tube in a state where the atleast one end is inserted in an opening formed in the holding member,wherein the holding member includes an insertion-guiding unit forguiding the at least one end of the arc tube to be inserted into theopening while preventing positional deviation of the at least one end,when the arc tube is rotated around the axis to be attached to theholding member.

According to this construction, by rotating the arc tube around thespiral axis with the end of the arc tube being in contact with theinsertion-guiding unit, the end of the arc tube can be easily insertedinto the opening formed in the holding member. It should be noted herethat the above longitudinal direction is the direction in which the endof the arc tube is wound around the axis, i.e., the spiral direction.

In particular, the insertion-guiding unit may be formed as a grooveextending in a direction in which the end of the arc tube is woundaround the axis.

Also, a part of the groove that comes in contact with a part of the endof the arc tube may have a shape corresponding to a shape of the part ofthe end of the arc tube.

According to this construction, the end of the arc tube can be guided tobe inserted into the opening of the holding member while the positionaldeviation of the arc tube is being prevented.

Further, the arc tube may include a pair of lead wires for an electrodeextending from the end of the arc tube, the opening may open toward adirection of the axis, and the holding member may allow the pair of leadwires to be inserted in the opening.

In particular, the opening may be formed at an angle of 20 to 60°inclusive with respect to the axis.

According to this construction, by making the lead wires in parallelwith the spiral-axis direction of the arc tube and moving the arc tubetoward the holding member in the spiral-axis direction before forexample attaching the arc tube to the holding member, the lead wires canbe easily inserted into the holding member through the opening.

Also, the holding member may include a covering unit that is formed sothat the opening is positioned at an edge of the covering unit, thecovering unit covering the end of the arc tube, and the opening may bepartially formed by a notch created in the covering unit and/or theinsertion-guiding unit.

According to this construction, by making the lead wires in parallelwith the spiral-axis direction of the arc tube and moving the arc tubetoward the holding member in the spiral-axis direction before forexample attaching the arc tube to the holding member, the lead wires canbe easily inserted into the holding member through the notch.

On the other hand, the end of the arc tube may be bonded within theholding member via a bonding agent.

Further, the insertion-guiding unit may include one or more inlets forinjecting the bonding agent in an area between

(a) the end of the arc tube placed in the holding member and

(b) the insertion-guiding unit of the holding member.

Alternatively, the holding member may include a wall at an internalsurface thereof for preventing the bonding agent from flowing outside.

This construction ensures that the arc tube is firmly held by theholding member.

Further, the arc tube may include a pair of lead wires for an electrodeextending from the end of the arc tube, and the holding member mayinclude a supporting unit for supporting the pair of lead wires whilekeeping a certain distance between the lead wires.

According to this construction, the lead wires are held with a certaindistance kept between them. Therefore, for example, crossing orentangling of the lead wires can be reduced.

Further, the arc tube may include a glass tube that is turned at asubstantially middle thereof and wound around the axis from the middle,to have a double-spiral structure.

According to this construction, the total height of the arc tube can bemade lower than an arc tube whose end portions are parallel with thespiral axis.

The above object of the present invention can also be achieved by amethod for assembling a low-pressure mercury lamp including: an arc tubewhose at least one end is wound around an axis entirely in alongitudinal direction thereof; and a holding member that includes aninsertion-guiding unit for guiding the at least one end of the arc tubeto be inserted into an opening formed in the holding member whilepreventing positional deviation of the at least one end, wherein aprocess of attaching the arc tube to the holding member includes thesteps of: making the at least one end of the arc tube come in contact,at a peripheral surface thereof, with the insertion-guiding unit of theholding member; and rotating, in a state where the at least one end ofthe arc tube is in contact with the insertion-guiding unit, the arc tubeand/or the holding member around the axis, so that the arc tube has arelative position with respect to the opening of the holding member.

According to this method, the arc tube can be easily attached to theholding member. Further, the end of the arc tube can be easily insertedinto the holding member by rotating the arc tube with its end being incontact with the insertion-guiding unit at a peripheral surface thereof.Therefore, automation of this process becomes possible. It should benoted here that the above longitudinal direction is the direction inwhich the end of the arc tube is wound around the axis, i.e., the spiraldirection.

Also, the arc tube may have a pair of lead wires for an electrodeextending from the end of the arc tube, the opening may open toward adirection of the axis, and the step of making the at least one end ofthe arc tube come in contact with the insertion-guiding unit of theholding member may be carried out in a state where the lead wires areparallel to the direction of the axis.

According to this method, by making the arc tube come in contact withthe holding member with the tips of the lead wires and the opening beingat the same positions in the spiral-axis direction, the lead wires canbe easily inserted into the holding member.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects, advantages and features of the invention willbecome apparent from the following description thereof taken inconjunction with the accompanying drawings that illustrate a specificembodiment of the invention. In the drawings:

FIG. 1 is a perspective view of a holder according to a conventionaltechnique as viewed diagonally from above;

FIG. 2 is a front view showing the overall construction of a compactself-ballasted fluorescent lamp according to a first embodiment of thepresent invention, with its right half being cut away;

FIG. 3 is a front view showing the construction of an arc tube accordingto the first embodiment, with being partially cut away;

FIG. 4 is a perspective view of a holder according to the firstembodiment as viewed diagonally from above;

FIG. 5 is a perspective view of the arc tube attached to the holderaccording to the first embodiment as viewed diagonally from above;

FIG. 6 is a perspective view of the arc tube attached to the holderaccording to the first embodiment placed upside down, as vieweddiagonally from above;

FIGS. 7A to 7C are diagrams for explaining processes for attaching thearc tube to the holder according to the first embodiment;

FIG. 8 is a perspective view of a holder according to a modification ofthe first embodiment;

FIG. 9 is a perspective view of a holder according to a secondembodiment of the present invention as viewed diagonally from above;

FIGS. 10A and 10B are diagrams for explaining processes for attachingthe arc tube to the holder according to the second embodiment;

FIG. 11 is a perspective view of a holder according to a modification ofthe second embodiment;

FIG. 12 is a perspective view of a holder according to a thirdembodiment of the present invention placed upside down, as vieweddiagonally from above;

FIG. 13 is a perspective view of a holder according to a modification ofthe third embodiment;

FIG. 14 is a perspective view of a holder according to a fourthembodiment of the present invention placed upside down, as vieweddiagonally from above;

FIG. 15 is a perspective view of a holder according to a modification ofthe fourth embodiment; and

FIG. 16 is a front view of another fluorescent lamp to which the presentinvention is applied.

BEST MODE FOR CARRYING OUT THE INVENTION First Embodiment

1. Construction of the Compact Self-ballasted Fluorescent Lamp

(1) Overall Construction

FIG. 2 is a front view showing the overall construction of a compactself-ballasted fluorescent lamp according to a first embodiment of thepresent invention, with its substantially half being cut away. Thecompact self-ballasted fluorescent lamp 1 is a 12 W lamp that is analternative to a 60 W incandescent lamp. It should be noted here that a60 W incandescent lamp has a maximum outer diameter of 60 mm and a totalheight of 110 mm.

As shown in the figure, the compact self-ballasted fluorescent lamp 1includes an arc tube 2 that has a double-spiral structure, an electronicballast 3 for lighting the arc tube 2, and a case 4 containing theelectronic ballast 3 and having a base 5.

FIG. 3 is a front view showing the construction of the arc tube 2 beingpartially cut away.

As shown in FIGS. 2 and 3, the arc tube 2 is formed by bending one glasstube 9. To be more specific, the glass tube 9 is turned at a turningportion 91 positioned substantially middle thereof, and is wound aroundan axis of spiral “A” from the turning portion 91 to its both ends 92and 93 at an angle of spiral.

It should be noted here that the glass tube 9 is wound at a spiral angle“α” (75° in the present embodiment) with respect to the spiral axis “A”from a position of the turning portion 91 until positions just beforeits end portions in the vicinity of the ends 92 and 93, and is wound ata spiral angle “β” (about 68° in the present embodiment) with respect tothe spiral axis “A” from positions at the start of the end portionsuntil positions of the ends 92 and 93. It should also be noted here thatin the present embodiment the end portions of the glass tube eachextend, as viewed from above, in a range of about ¼ winds from the endof the glass tube in a direction where the turning portion 91 ispositioned.

The spiral angle of the glass tube 2 with respect to the spiral axis “A”is changed in the vicinity of the ends 92 and 93, for the purpose ofmaking the ends 92 and 93 away from portions of the glass tube 9adjacent to the ends 92 and 93 in a direction parallel to the spiralaxis “A” (hereafter simply referred to as a “spiral-axis direction”),and thereby allowing the arc tube 2 to be easily held by a holder, whichis described later.

Hereafter, the direction in which the glass tube 9 is wound around thespiral axis “A” at the spiral angle (the direction in which the glasstube 9 is wound from its turning portion to ends) is referred to as the“spiral direction”. For the compact self-ballasted fluorescent lamp 1,the side where the tuning portion 91 of the arc tube 2 is positioned isassumed to be the “upper side”, and the side where the base 5 ispositioned is assumed to be the “lower side”.

The glass tube 9 has a tube inner diameter of 7.4 mm, a tube outerdiameter of 9.0 mm. A gap between every adjacent portions of the glasstube 9 in the spiral-axis direction, excluding the end portions, isabout 1 mm, and a gap between the ends 92 and 93 and adjacent portionsof the glass tube 9 is about 6 mm at the maximum. The glass tube 9 iswound from the turning portion 91 to the ends 92 and 93 around thespiral axis “A” by substantially 4.5 winds. The arc tube 2 with adouble-spiral structure has a total height of 60 mm and a maximum outerdiameter of 37 mm.

As shown in FIG. 3, an electrode 8 is sealed at the end 93 of the glasstube 9. As one example, a coil electrode made of tungsten is used as theelectrode 8. The coil electrode is supported by a pair of lead wires 8 aand 8 b temporarily fixed via bead glass 82 (by way of a “bead glassmounting method”).

Although not shown in the figure, an electrode is also sealed at the end92 of the glass tube 9. In the figure, a pair of lead wires 7 a and 7 bconnected to the coil electrode (not shown) extends from the end 92.

As shown in FIG. 3, an exhaust tube 85 for exhausting the inside of theglass tube 9 is sealed at one end (the end 93 in this example) of theglass tube 9 at the time when the electrode 8 is sealed there. It shouldbe noted here that the distance between the electrodes within the glasstube 9 is 400 mm.

Here, a rare-earth phosphor 95 is applied to the inner surface of theglass tube 9. The phosphor 95 used here is a mixture of three types ofphosphors respectively emitting red, green, and blue light, e.g.,Y₂O₃:Eu, LaPO₄:Ce, Tb, and BaMg₂Al₁₆O₂₇:Eu, Mn.

Within the glass tube 9, mercury is singly enclosed by an amount ofabout 5 mg, and also, a rare gas such as a mixture gas of argon and neon(with a capacity ratio of neon in the mixture gas being substantially25%) is enclosed at 400 Pa via the exhaust tube 85.

Here, the finished structure of the glass tube 9 in which the phosphorlayer 95 has been applied to the inner surface, the rare gas has beenenclosed inside, etc., corresponds to the arc tube 2. Hereafter, anexplanation given using the arc tube 2 assumes that both ends of the arctube 2 corresponding to the ends 92 and 93 of the glass tube 9 arereferred to as “ends 92 and 93 of the arc tube 2”, a portion of theglass tube 9 in the vicinity of its end 92 is referred to as an “endportion 92 a of the arc tube 2”, and a portion of the glass tube 9 inthe vicinity of its end 93 is referred to as an “end portion 93 a of thearc tube 2”. It should be noted here that the end portions 92 a and 93 aof the arc tube 2 correspond to the “end that is wound around the axisentirely in the longitudinal direction” referred to in the claims of thepresent invention.

As shown in FIG. 2, the ends 92 and 93 of the arc tube 2 are insertedinto a holder 6 and bonded to the holder 6 via such a bonding agent assilicone (not shown). The holder 6 is described in detail later.

As shown in FIG. 2, a substrate 31 is attached at the backside of theholder 6 (at the side where the base 5 is positioned). A plurality ofelectronic components 32, 33, etc. for lighting the arc tube 2 aremounted on the substrate 31. It should be noted here that theseelectronic components 32, 33, etc. constitute the electronic ballast 3.

The case 4 is made of a synthetic resin and is in a tubular shape havinga larger diameter as closer to its top. The holder 6 to which the arctube 2 and the substrate 31 are attached is placed in the opening of thecase 4 from the side (lower side) where the electronic ballast 3 ispositioned and is fixed therein. The base 5 (e.g., an E26 type base) isattached to the bottom end of the case 4, i.e., the side of the case 4opposite to the opening. It should be noted here that electricalconnection between the base 5 and the electronic ballast 3 is not shownin FIG. 2.

The base 5 is of a screw type, with its central axis being substantiallymatching the spiral axis “A” of the arc tube 2. Hereafter, the centralaxis of the base 5 may also be referred to as the “central axis of thecompact self-ballasted fluorescent lamp 1”.

(2) Construction of the Holder

FIG. 4 is a perspective view of the holder 6 as viewed diagonally fromabove. FIG. 5 is a perspective view of the holder 6 to which the arctube 2 is attached, as viewed diagonally from above. FIG. 6 is aperspective view of the holder 6 to which the arc tube 2 is attached asviewed diagonally from below.

As shown in FIGS. 4 to 6, the holder 6 is in a cylindrical shape whoseone end is closed. The holder 6 has a bottom wall 61 and a peripheralwall 62. The holder 6 has two insertion openings 63 and 64 at the bottomwall 61. The insertion openings 63 and 64 are for allowing the ends 92and 93 of the arc tube 2 to be inserted therethrough. As shown in FIG.6, the ends 92 and 93 of the arc tube 2 that have been inserted throughthe insertion openings 63 and 64 of the holder 6 are bonded via abonding agent 65 such as silicone. In this way, the arc tube 2 is heldby the holder 6.

Here, in the front view of the insertion openings 63 and 64 viewed inthe direction where the ends 92 and 93 are moved (a track to be drawn bythe ends 92 and 93) when the ends 92 and 93 of the arc tube 2 areinserted into the holder 6 through the insertion openings 63 and 64, an“area in short of the insertion opening in the direction where the ends92 and 93 are moved” is assumed to be an “area-before the insertionopening”, and an “area beyond the insertion opening in the directionwhere the ends 92 and 93 are moved” is assumed to be an “area after theinsertion opening”.

It should be noted here that the bottom wall 61 is substantiallyperpendicular to a central axis “B” of the peripheral wall 62 (hereafterreferred to as the “central axis “B” of the holder 6”), in such a mannerthat a center “O2” of the bottom wall 61 is positioned on the centralaxis “B” of the holder 6. Also, the arc tube 2 is held by the holder 6with the spiral axis “A” of the arc tube 2 substantially matching thecentral axis “B” of the holder 6.

As shown in FIG. 4, the insertion openings 63 and 64 are in a circularshape corresponding to the outer shape of the ends 92 and 93, so as toallow the ends 92 and 93 to be inserted therethrough. The insertionopenings 63 and 64 are formed on a plane perpendicular to the bottomwall 61.

The centers “O3” and “O4” of the insertion openings 63 and 64 arepositioned on a track “X” to be drawn on a plane by the centers of crosssections of the ends 92 and 93 of the arc tube 2 when the arc tube 2 isrotated in the spiral direction (to right in FIG. 4) with the spiralaxis “A” of the arc tube 2 matching the central axis “B” of the holder6.

To be more specific, a distance between the centers “O3” and “O4” of theinsertion openings 63 and 64 via the central axis “B” of the holder 6 (adistance “D₂” in FIG. 4) is equal to a diameter of the arc tube 2 formedby the glass tube 9 being wound around the spiral axis “A” (a diameter“D₁” in FIG. 3).

The centers “O3” and “O4” of the insertion openings 63 and 64 arepositioned at substantially the middle of the bottom wall 61 in itsthickness direction, on a plane parallel to the surface of the bottomwall 61. Each of the insertion openings 63 and 64 is formed in such amanner that an upper half of its periphery protrudes in a semi-circularshape from the bottom wall 61 and a lower half of its periphery recessesin a semi-circular shape from the bottom wall 61.

In areas before the insertion openings 63 and 64, guide grooves 66 and67 are formed. The guide grooves 66 and 67 are provided for guiding theends 92 and 93 of the arc tube 2 toward the insertion openings 63 and 64while preventing deviation of the ends 92 and 93 of the arc tube 2. Toinsert the ends 92 and 93 of the arc tube 2 into the holder 6, the endportions 92 a and 93 a are first placed to come in contact with theguide grooves 66 and 67. In this state, the arc tube 2 is then rotatedaround the spiral axis “A” in the spiral direction, so that the ends 92and 93 of the arc tube 2 are guided to the insertion openings 63 and 64by the guide grooves 66 and 67. It should be noted here that the guidegrooves 66 and 67 correspond to the “insertion-guiding unit” referred toin the claims of the present invention.

The guide grooves 66 and 67 are formed in the spiral direction, incorrespondence with the outer shape of the end portions 92 a and 93 athat have been wound in a double spiral. The guide grooves 66 and 67 arecontinuous to the lower halves of the peripheries of the insertionopenings 63 and 64. To be more specific, the guide grooves 66 and 67have the same semi-circular cross sections as the semi-circular crosssections of the lower parts of the end portions 92 a and 93 a of the arctube 2, and allow the lower parts of the end portions 92 a and 93 a ofthe arc tube 2 to come in contact. It should be noted here that thesurfaces of the guide grooves 66 and 67 with which the end portions 92 aand 93 b come in contact are referred to as the “contact surfaces 66 aand 67 a”. The guide grooves 66 and 67 are formed deeper as they arecloser to the insertion openings 63 and 64.

To be more specific, the guide grooves 66 and 67 have the contactsurfaces 66 a and 67 a being wound in the same manner as that for theend portions 92 a and 93 a of the arc tube 2, i.e., wound around thecentral axis “B” of the holder 6 at the spiral angle “β”.

On the other hand, in areas after the insertion openings 63 and 64,covering units 68 and 69 are formed. The covering units 68 and 69 areprovided for covering the ends 92 and 93 and the end portions 92 a and93 a of the arc tube 2 inserted in the holder 6. As shown in FIG. 4, thecovering units 68 and 69 are continuous from the upper halves of theperipheries of the insertion openings 63 and 64, and extend in thespiral direction of the end portions 92 a and 93 a of the arc tube 2.The covering units 68 and 69 and are each formed in the shape of anarch.

To be more specific, the covering units 68 and 69 have the semi-circularcross sections corresponding to the semi-circular cross sections of theupper parts of the end portions 92 a and 93 a of the arc tube 2, andallow the upper parts of the end portions 92 a and 93 a of the arc tube2 to be fit therein. The arches of the covering units 68 and 69 areformed lower as they are less closer to the insertion openings 63 and64.

2. Processes for Assembling Compact Self-ballasted Fluorescent Lamp

The following describes processes for assembling the compactself-ballasted fluorescent lamp 1 with the above-described construction,in particular, the processes for attaching the arc tube 2 to the holder6. FIGS. 7A to 7C are diagrams for explaining the processes forinserting the arc tube 2 into the holder 6 through the insertionopenings 63 and 64.

First, the arc tube 2 with a double-spiral structure and the holder 6for holding the arc tube 2 are prepared. The arc tube 2 and the holder 6are aligned so that the spiral axis “A” of the arc tube 2 substantiallymatches the central axis “B” of the holder 6, and the ends 92 and 93 ofthe arc tube 2 are positioned above the insertion openings 63 and 64 inthe direction of the central axis “B”. The arc tube 2 is then movedtoward the holder 6 along the central axis “B” of the holder 6 in thedirection indicated by an arrow shown in FIG. 7A, and the arc tube 2 isplaced on the holder 6 in such a manner that the end portions 92 a and93 a are fit in the guide grooves 66 and 67.

Here, the lower parts of the end portions 92 a and 93 a of the arc tube2 are in contact with the contact surfaces 66 a and 67 a of the guidegrooves 66 and 67. Because the guide grooves 66 and 67 are formed tohave the contact surfaces 66 a and 67 a along the lower parts of the endportions 92 a and 93 a of the arc tube 2, the arc tube 2 can be placedstably on the holder 6.

Also, the guide groove 66 (or 67) is provided in an area before theinsertion opening 63 (or 64) so as to extend in a wide range “C” (seeFIG. 4) from the insertion opening 63 (or 64) to a position of about ⅕of one wind around the central axis “B” of the holder 6. Therefore, theend portions 92 a and 93 a of the arc tube 2 can be easily placed on theguide grooves 66 and 67.

Next, the arc tube 2 placed on the holder 6 is rotated around the spiralaxis “A” in the spiral direction indicated by an arrow in FIG. 7B, sothat the ends 92 and 93 of the arc tube 2 are moved toward the insertionopenings 63 and 64 along the guide grooves 66 and 67. As shown in FIG.7C, the ends 92 and 93 of the arc tube 2 are finally inserted into theholder 6 through the insertion openings 63 and 64.

Here, the guide grooves 66 and 67 are formed as continuous to theinsertion openings 63 and 64 in the spiral direction of the end portions92 a and 93 a of the arc tube 2. By such guide grooves 66 and 67, theends 92 and 93 of the arc tube 2 are guided to the insertion openings 63and 64 and smoothly inserted into the holder 6 through the insertionopenings 63 and 64, simply by rotating the arc tube 2 around the spiralaxis “A” matching the central axis “B” of the holder 6. During theinsertion, the positional deviation of the arc tube 2 placed on theguide grooves 66 and 67 is also prevented. In this way, the conventionalproblem of difficulties in inserting ends of an arc tube into theinsertion openings 963 and 964 of the holder 906 can be solved.

As described above, the ends 92 and 93 of the arc tube 2 can be insertedinto the holder 6 through the insertion openings 63 and 64 simply byrotating the arc tube 2 around the spiral axis “A” after placing the endportions 92 a and 93 a of the arc tube 2 on the guide grooves 66 and 67of the holder 6. Therefore, automation of this process becomes possible.

Further, in the compact self-ballasted fluorescent lamp 1 in which thearc tube 2 is attached to the holder 6 with the above-describedconstruction, the end portions 92 a and 93 a of the arc tube 2 arecovered by the covering units 68 and 69. This means that electrodes andthe like sealed at the ends 92 and 93 of the arc tube 2 can also becovered up.

3. Others

i) Covering Unit

Although the first embodiment describes the case where the coveringunits 68 and 69 are formed in the areas after the insertion openings 63and 64 of the holder 6, the covering units 68 and 69 may not necessarilybe provided. This is because easy insertion of the arc tube 2 into theholder 6 through the insertion openings 63 and 64 only requires theguide grooves 66 and 67 formed in the areas before the insertionopenings 63 and 64.

FIG. 8 is a perspective view of a holder in which covering units are notprovided.

As shown in the figure, the holder 106 has, at its bottom wall 161,insertion openings 163 and 164 and guide grooves 166 and 167. The guidegrooves 166 and 167 have the same constructions as the guide grooves 66and 67 described in the first embodiment. The insertion openings 163 and164 are composed of openings formed in the bottom wall 161 by removingthe covering units 68 and 69 described in the first embodiment andopenings corresponding to the insertion openings 63 and 64 described inthe first embodiment formed at the edges of the guide grooves 66 and 67.

The holder 106 does not have covering units (68 and 69), and thereforecan have the bottom wall 161 being flat without any recession andprotrusion. Such a flat bottom wall can represent an improvement in thedesign. In this case where the covering units are not provided, however,the end portions 92 a and 93 a of the arc tube 2 need to be insertedinto the holder 106 to such a degree that enables electrodes sealed atthe ends 92 and 93 to be covered up.

ii) Guide Groove

(Shape of Cross Section)

The first embodiment describes the case where the guide grooves 66 and67 have the contact surfaces 66 a and 67 a with which the lower parts ofthe end portions 92 a and 93 a of the arc tube 2 come in contact, andsuch guide grooves 66 and 67 prevent the positional deviation of the arctube 2 in a direction perpendicular to the spiral axis “A” (horizontaldirection) when the arc tube 2 is rotated for its attachment. However,the lower parts of the end portions 92 a and 93 a of the arc tube 2 maynot necessarily come in contact with substantially the entire guidegrooves 66 and 67, as long as the guide grooves 66 and 67 can preventthe positional deviation of the arc tube 2 in the directionperpendicular to the spiral axis “A” when the arc tube 2 is rotated.

For example, the guide grooves 66 and 67 may be formed to have a crosssection in a rectangular shape or a V-shape. The guide grooves 66 and 67may further be formed to have a semi-circular cross section that ispartially the same as the semi-circular cross section of the lower partsof the end portions 92 a and 93 a of the arc tube 2. The guide grooves66 and 67 having cross sections of any of the above shapes can alsoguide the ends 92 and 93 of the arc tube 2 to the insertion openings 63and 64.

(Shape of Vertical Section)

The first embodiment describes the case where the guide grooves 66 and67 have the contact surfaces 66 a and 67 a that are continuous in thespiral direction along the end portions 92 a and 93 a of the arc tube 2,so that the guide grooves 66 and 67 can guide, without deviation, theends 92 and 93 of the arc tube 2 toward the insertion openings 63 and 64in the spiral direction when the arc tube 2 is rotated around the spiralaxis “A”.

However, the guide grooves 66 and 67 do not need to have the contactsurfaces 66 a and 67 a that are continuous in the spiral direction, aslong as the guide grooves 66 and 67 enable the arc tube 2 before beinginserted into the holder 6 to be placed thereon in a stable manner andcan guide without deviation the ends 92 and 93 toward the insertionopenings 63 and 64 in the spiral direction when the arc tube 2 isrotated around the spiral axis “A”.

As one example, the guide grooves 66 and 67 may have discontinuescontact surfaces with which the end portions 92 a and 93 a of the arctube 2 before being inserted into the holder 6 come in contact at two ormore positions thereof in the spiral direction. In this case, the endportions 92 a and 93 a of the arc tube 2 need to keep in contact withthe contact surfaces at two or more positions thereof while the arc tube2 is being rotated.

As a specific example of such, the guide grooves 66 and 67 may beprovided with contact parts arranged at certain intervals for allowingthe end portions 92 a and 93 a of the arc tube 2 to come in contact. Inthis case, too, the same effects as produced by the continuous contactsurfaces 66 a and 67 a described above can be produced.

iii) Insertion Opening

The first embodiment describes the case where the insertion openings 63and 64 formed at the bottom wall 61 of the holder 6 are in such acircular shape corresponding to the outer shape of the ends 92 and 93 ofthe arc tube 2. In the case of the arc tube 2 whose ends have an outershape different from the shape described in the first embodiment, it ispreferable to form the insertion openings 63 and 64 in such a shapedetermined accordingly.

However, the shape of the insertion openings 63 and 64 may notnecessarily be the same as the outer shape of the ends 92 and 93 of thearc tube 2, as long as the insertion openings 63 and 64 allow the ends92 and 93 of the arc tube 2 to be inserted therethrough into the holder6.

One specific example is a case where the outer shape of the ends 92 and93 and the end portions 92 a and 93 a of the arc tube 2 is circular andthe shape of the insertion openings is substantially square with its oneside being a diameter of the circular outer shape of the ends 92 and 93and the end portions 92 a and 93 a of the arc tube 2.

In this case, however, gaps larger than necessary are formed between thecorners of the insertion openings and the end portions 92 a and 93 a ofthe arc tube 2 inserted therethrough. The bonding agent 65 may flowthrough these gaps when the ends 92 and 93 of the arc tube 2 are bondedto the holder 6.

Also, although a plane on which the insertion openings 63 and 64 areprovided is perpendicular to the bottom wall 61 and includes the centralaxis “B” thereon, the plane where the insertion openings 63 and 64 areprovided may not necessarily include the central axis “B” thereon. Asone example, the plane where the insertion openings 63 and 64 areprovided may be a plane forming a predetermined angle with respect tothe radius direction of the bottom wall 61.

Further, although the first embodiment describes the case where thecenters of the insertion openings 63 and 64 are positioned atsubstantially the middle of the bottom wall 61 in its thicknessdirection, on a plane substantially parallel to the surface of thebottom wall 61, the positions of the centers of the insertion openings63 and 64 in the direction of the central axis “B” may not necessarilybe the same as the position of the bottom wall 61, as long as the guidegrooves 66 and 67 are provided to extend toward the insertion openings63 and 64 in the spiral direction of the end portions 92 a and 93 a ofthe arc tube 2. For example, the insertion openings 63 and 64 mayentirely protrude from the bottom wall 61, or may be entirely embeddedbelow the bottom wall 61.

Second Embodiment

The inventors of the present application examined the construction ofthe holder 6 that enables the ends 92 and 93 of the arc tube 2 to beeasily inserted into the holder 6, and the method for attaching the arctube 2 to the holder 6. As a result, the inventors discovered that theholder 6 in which the guide grooves 66 and 67 are provided in the areasbefore the insertion openings 63 and 64 enable the ends 92 and 93 of thearc tube 2 to be easily inserted into the holder 6 as described in thefirst embodiment.

However, the inventors found difficulties in attaching the arc tube 2 tothe holder 6 described in the first embodiment, when the arc tube 2 haslead wires 7 a, 7 b, 8 a, and 8 b that are for supporting coilelectrodes and extend from the ends 92 and 93. To be specific, theinventors found difficulties in inserting the lead wires 7 a, 7 b, 8 a,and 8 b smoothly through the insertion openings 63 and 64 of the holder6.

The inventors then made preliminarily examinations on the constructionof a holder that enables ends of an arc tube from which lead wires forelectrodes extend, to be easily inserted into the holder, and also onthe method for attaching the arc tube to the holder. As a result, theinventors discovered that the lead wires are inserted relatively easilythrough the insertion openings by bending the lead wires in a directionparallel to the spiral-axis direction and inserting them through theinsertion openings in the spiral-axis direction.

1. Construction of the Holder

FIG. 9 is a perspective view of a holder that enables lead wires forelectrodes to be inserted easily into the holder. This holder 206results from the preliminary examinations described above. The holder206 is characterized in that its insertion openings 263 and 264 areformed so as to provide openings as viewed from above, for enabling thelead wires 207 a, 207 b, 208 a, and 208 b (see FIG. 10) substantiallyparallel to the central axis “B” of the holder 206, to be easilyinserted therethrough when the arc tube 202 is attached to the holder206.

The insertion openings 263 and 264 of the holder 206 are inclined sothat their upper parts are shifted in the direction where the coveringunits 268 and 269 are provided. To be specific, the insertion openings263 and 264 are formed in such a manner that a plane where the insertionopening is provided is inclined at an angel “γ”, e.g., 40° with respectto the central axis “B” of the holder 206 as shown in FIG. 9. As viewedfrom above in the direction of the central axis “B” in FIG. 9, theinsertion openings 263 and 264 are formed to provide openings betweenthe covering units 268 and 269 and the guide grooves 266 and 267.

2. Attachment Processes

FIGS. 10A and 10B are diagrams for explaining processes for attaching anarc tube having lead wires for electrodes, to a holder. First, the leadwires 207 a, 207 b, 208 a, and 208 b indicated by bold lines in FIG. 10Aextending from the ends 293 (and 294) of the arc tube 202 are bent tothe side opposite to the turning portion 91 in a direction parallel tothe spiral-axis direction (“A” in the figure) of the arc tube 202, atpositions close to the ends 293 (and 294) of the arc tube 202. The leadwires 207 a, 207 b, 208 a, and 208 b after being bent are indicated byinterrupted lines in FIG. 10A.

Following this, the arc tube 202 and the holder 206 are aligned so thatthe spiral axis “A” of the arc tube 202 substantially matches thecentral axis “B” of the holder 206, and that the lead wires 207 a, 207b, 208 a, and 208 b are positioned to enter in the openings formedbetween the covering units 268 and 269 and the guide grooves 266 and 267of the holder 206 as viewed from above. Then, the arc tube 202 is movedtoward the holder 206 in the direction indicated by an arrow in FIG.10B, i.e., in the direction of the spiral axis “A”. Here, the arc tube202 is moved while its aligned position in a direction perpendicular tothe spiral axis “A” is being maintained.

Here, the insertion openings 263 and 264 of the holder 206 are inclinedwith respect to the spiral axis “A” of the arc tube 202 (the centralaxis “B” of the holder 206). As viewed from above, therefore, theinsertion openings 263 and 264 provide the openings formed between thecovering units 268 and 269 and the guide grooves 266 and 267. The leadwires 207 a, 207 b, 208 a, and 208 b bent to be substantially parallelto the spiral axis “A” can be easily inserted into the holder 206through such openings formed between the covering units 268 and 269 andthe guide grooves 266 and 267 as shown in FIG. 10B.

The arc tube 202 is further moved toward the holder 206, so that the endportions 293 a (and 294 a) of the arc tube 202 are fit in the guidegrooves 266 and 267 of the holder 206. The subsequent processes are thesame as the processes described in the first embodiment.

3. Others

i) Inclination of Insertion Opening

Although the second embodiment describes the case where the insertionopenings 263 and 264 are inclined at an angle of 40° (“β” in the figure)with respect to the central axis “B” of the holder 206 as show in FIG.9, the angle of inclination “γ” should not be limited to 40°. The angleof inclination “γ” may be set at any value smaller than 90°. However, itis preferable that the angle “λ” is in a range of 20 to 60° inclusive.

This range is determined due to the following reason. When the angel “λ”is smaller than 20°, the openings formed between the covering units 268and 269 and the guide grooves 266 and 267 are so small that insertingthe lead wires 207 a, 207 b, 208 a, and 208 b into the holder 206through the openings becomes difficult.

On the other hand, when the angel “λ” is larger than 60° the bondingagent used for bonding the ends 293 and 294 of the arc tube 202 to theholder 206 may flow through the insertion openings 263 and 264.

Also, although the second embodiment describes the case where theinsertion openings 263 and 264 are formed in such a manner that theupper halves thereof (the peripheries of the ends of the covering units268 and 269) and the lower halves thereof (the peripheries of the endsof the guide grooves 266 and 267) are inclined at the same angles withrespect to the central axis “B” of the holder 206, only the upper halvesor the lower halves of the insertion openings 263 and 264 may beinclined with respect to the central axis “B” of the holder 206, or theupper halves and the lower halves of the insertion openings 263 and 264may be inclined at different angles with respect to the central axis “B”of the holder 206.

ii) Modification of the Second Embodiment

The second embodiment describes the case where the insertion openings263 and 264 are inclined so as to provide openings between the coveringunits 268 and 269 and the guide grooves 266 and 267 as viewed fromabove, for the purpose of enabling the lead wires 207 a, 207 b, 208 a,and 208 b to be easily inserted into the holder 206 through theinsertion openings 263 and 264. However, the covering units 268 and 269and the guide grooves 266 and 267 may have other constructions toprovide openings between them.

FIG. 11 is a perspective view of a holder having notches formed in thevicinity of its insertion openings. As shown in the figure, the holder206 has notches 270 a, 270 b, 271 a, and 271 b formed in the coveringunits 268 and 269 and the guide groves 266 and 267, so as to widen theinsertion openings 263 and 264 as viewed from above in the direction ofthe central axis “B”. In the case of this holder 206 as in the secondembodiment, the lead wires 207 a, 207 b, 208 a, and 208 b extending fromthe ends 293 and 294 of the arc tube 202 can be easily inserted into theholder 206 by bending the lead wires 207 a, 207 b, 208 a, and 208 b inparallel with the spiral axis “A” of the arc tube 202.

Also, although the present modification describes the case where thenotches 270 a and 271 a are formed in the covering units 268 and 269 andthe notches 270 b and 271 b are formed in the guide grooves 266 and 267,notches may be formed only in the covering units 268 and 269 or in theguide grooves 266 and 267. In either case, however, the total area ofthe notches formed is to be substantially the same as the total area ofthe notches 270 a, 270 b, 271 a, and 271 b formed in the covering units268 and 269 and the guide grooves 266 and 267, so that the lead wires207 a, 207 b, 208 a, and 208 b can be easily inserted into the holder206.

Although the notches 270 a, 270 b, 271 a, and 271 b are each formed tohave substantially a semi-circular shape as viewed from above in thedirection of the central axis “B” in FIG. 11, the notches 270 a, 270 b,271 a, and 271 b may be each formed to have another shape such as aV-shape and a rectangular shape as viewed from above.

Further, slits may be formed instead of the notches 270 a, 270 b, 271 a,and 271 b. In this case, too, the same effects as produced by thenotches 270 a, 270 b, 271 a, and 271 b can be produced, althoughinserting the lead wires 207 a, 207 b, 208 a, and 208 b therethroughbecomes more difficult in the case where the slits are provided.

Also, the above examples and the second embodiment may be combined. Forexample, the insertion openings 263 and 264 may be formed in such amanner that the upper halves of their peripherals are inclined withrespect to the central axis “B” of the holder 206, and the notches 270 band 271 b are formed in the guide grooves 266 and 267.

Third Embodiment

The inventors of the present application examined the construction ofthe holder that enables the ends of the arc tube to be easily insertedtherein and the method for attaching the arc tube to the holder (firstembodiment), and the construction of the holder 206 that enables thelead wires 207 a, 207 b, 208 a, and 208 b extending from the ends 293and 294 of the arc tube 202 to be smoothly inserted therein and themethod for attaching the arc tube 202 to the holder 206 (secondembodiment).

As a result, the inventors came up with the idea to provide the guidegrooves 66 and 67 in the areas before the insertion openings 63 and 64of the holder 6, and the idea to widen the insertion openings 263 and264 as viewed from above, as described in the first and secondembodiments.

However, the inventors are encountered with a new problem that thebonding agent cannot be injected by a sufficient amount between (a) theholder 206 and (b) the ends and the end portions of the arc tube 202,when the ends of the arc tube 202 inserted in the holder 206 are bondedto the holder 206 via the bonding agent.

FIG. 12 is a perspective view of a holder that enables the bonding agentto be injected by a sufficient amount in an area where the arc tube andthe holder are bonded together. As shown in the figure, the holder 306in the present embodiment has a plurality of, e.g, three, inlets 380 atbottoms 366 a and 367 a of the guide grooves 366 and 367. The inlets 380are provided for injecting the bonding agent between the end portions ofthe arc tube and the surfaces (with which the arc tube comes in contact)of the guide grooves 366 and 367.

It should be noted here that because the holder 306 is placed upsidedown in FIG. 12, the guide grooves 366 and 367 are each viewed in theshape of an arch, and also that the inlets formed in the guide groove367 are not shown in the figure as hidden by a peripheral wall 362.

This construction ensures that the bonding agent is injected by asufficient amount between the surfaces of the guide grooves 366 and 367and the end portions of the arc tube in contact therewith or opposedthereto, through the inlets 380 formed in the bottoms 366 a and 367 a ofthe guide grooves 366 and 367. This construction ensures that the arctube and the surfaces of the guide grooves 366 and 367 are bonded firmlytogether.

Because the three inlets 380 are arranged in the spiral direction of theend portions of the arc tube in the bottoms 366 a and 367 a of the guidegrooves 366 and 367 of the holder 306, the bonding agent can be filledsubstantially uniformly in an area where the end portions of the arctube are in contact with or opposed to the guide grooves 366 and 367.

With this construction, an amount of bonding agent to be injected can beoptimized. Further, because the inlets 380 are provided in the bottoms366 a and 367 a of the guide grooves 366 and 367, the inlets 380 cannotbe viewed from outside the holder 306 after the arc tube is bonded tothe holder 306. Therefore, the inlets 380 do not cause deterioration inthe design.

FIG. 13 is a perspective view of a holder that can also solve theabove-described problem. This holder 306 includes enclosure walls 381and 382 to prevent flowing out of the bonding agent injected in thevicinity of the ends of the arc tube. These enclosure walls 381 and 382are formed on the back surface of the bottom wall 361 so as to enclosethe ends and the end portions of the arc tube inserted in the holder306.

This construction prevents the bonding agent injected in the vicinity ofthe ends of the arc tube from flowing toward the center of the backsurface of the bottom wall 361, thereby ensuring that the bonding agentblocked in the enclosure walls 381 and 382 firmly bonds the ends and theend portions of the arc tube to the holder 306.

Also, because the enclosure walls 381 and 382 are formed along the endsand the end portions of the arc tube, the arc tube and the enclosurewalls 381 and 382 are bonded together via the bonding agent. Thisenables the arc tube and the holder 306 to be bonded firmly.

It should be noted here that the enclosure walls 381 and 382 come incontact with the arc tube when the ends of the arc tube are inserted inthe holder 306. The enclosure walls 381 and 382 therefore also have thefunction of blocking the insertion of the arc tube. Accordingly, theenclosure walls 381 and 382 enable the arc tube to be inserted into theholder 306 by substantially a uniform distance. Therefore, the enclosurewalls 381 and 382 can function as walls to block the insertion of thearc tube even in a case where the bonding agent is not injected in anarea enclosed by the enclosure walls 381 and 382.

Fourth Embodiment

The inventors of the present application succeeded in easily attachingthe arc tube to the holder and bonding the arc tube and the holderfirmly together, by utilizing the holders 6, 206, and 306 described inthe first to third embodiments.

However, the inventors were encountered with a new problem whenattaching the substrate on which the electronic ballast is mounted tothe holder, and connecting the lead wires that extend from the ends ofthe arc tube to the surface of the substrate where the base is provided.The problem is that the lead wires are crossed or entangled within theholder.

The inventors solved the above problem by providing the holder withsupporting units for supporting the lead wires. The following describesthe construction of the supporting units.

FIG. 14 is a perspective view of a holder having such supporting units.As shown in the figure, this holder 406 has supporting units 491 and 492for supporting lead wires, at the back surface of the bottom wall 461 inthe vicinity of the ends of the arc tube inserted in the holder 406.

The supporting unit 491 (or 492) is made up of a supporting base 491 a(or 492 a) provided at the back surface of the bottom wall 461, and apair of supporting slits 491 b (or 492 b) formed in the supporting base491 a (or 492 a) for supporting a pair of lead wires.

It should be noted here that the pair of supporting slits 491 b (or 492b) formed in the supporting base 491 a (or 492 a) are positioned at apredetermined interval, to support a pair of lead wires with a certaindistance being kept between the lead wires.

When the substrate is attached to this holder 406, pairs of lead wiresextending from the ends of the arc tube fixed to the holder 406 arefirst set in the supporting slits 491 b and 492 b of the supportingunits 491 and 492, in such a manner that the lead wires are not crossedor entangled within the holder 6.

The lead wires supported at the supporting slits 491 b and 492 b arethen lead outside of the holder 406, in such a manner that the leadwires are not crossed or entangled within the holder 6. After this, thesubstrate on which the electronic ballast is mounted is attached, forexample, to the peripheral wall 462 of the holder 406.

This construction prevents the lead wires from being entangled. Also,because the pairs of lead wires extending from the ends of the arc tubeare supported at the supporting slits 491 b and 492 b with a certaindistance being kept between the lead wires in each pair, the lead wiresdo not come in contact with each other (i.e. the lead wires are notshort-circuited).

It should be noted here that the supporting units 491 and 492 may notnecessarily be formed at the back surface of the bottom wall 461 of theholder 406 but may be formed at other positions. As one example, thesupporting units 491 and 492 may be formed directly in the peripheralwall 462 of the holder 406 as that is shown in FIG. 15. In this case,two supporting units 495 and 496 are respectively made up of a pair ofsupporting slits 495 a and a pair of supporting slits 496 a formed inthe peripheral wall 462. The supporting slits 495 a and the supportingslits 496 a are positioned away from each other, e.g., positioned asopposed to each other with respect to the central axis of the holder406.

(Modifications)

Although the present invention is described based upon the aboveembodiments, the contents of the present invention should not be limitedto specific examples shown in the above embodiments. For example, thefollowing modifications are possible.

1. Holding Member

Although the above embodiments describe the case where the holdingmember is made up of a bottom wall and a peripheral wall that areconnected together, the holding member may be made up of only a bottomwall. In this case, too, the provision of insertion openings,insertion-guiding units, covering units etc. formed at the bottom wallof the holding member can produce the same effects as produced in theabove embodiments.

Although the above embodiments describe the case where the arc tube isheld by the holding member (holder) with the spiral axis of the arc tubematching the central axis of the holding member, the arc tube may beheld by the holding member with the spiral axis of the arc tube beinginclined with respect to the central axis of the holding member.

In this case, for example, the insertion openings, insertion-guidingunits, and covering units are formed to be inclined with respect to thecentral axis of the holding member according to the inclination of thecentral axis of the bottom wall with respect to the spiral axis of thearc tube. In this case where the arc tube is inclined with respect tothe holding member holding the arc tube, the insertion openings,insertion-guiding units, and covering units can have the same positionalrelationship as that described in the above embodiments by positioningthem based upon the position of the spiral axis of the arc tube on whichthe center of the bottom wall of the holding member is positioned. Bydoing so, the same effects as produced in the above embodiments can beproduced.

Although the above embodiments describe the case where the central axisof the holding member and the spiral axis of the arc tube substantiallymatch on the same line, these axes may not necessarily match. In thecase where these axes do not match, too, the same effects as produced inthe above embodiments can be produced by positioning the insertionopenings, insertion-guiding units, covering units etc. of the holdingmember based upon the position of the spiral axis of the arc tube.

2. Shape of Arc Tube

Although the above embodiments describe the case where the presentinvention is applied to an art tube having a double-spiral structure,the present invention may be applied to arc tubes with other structures.As one example, the present invention may be applied to an arc tubecomposed of a plurality of U-shaped glass tubes that are connected withone another, e.g., a triple-tube arc tube composed of three U-shapedglass tubes or a quad-tube arc tube composed of four U-shaped glasstubes. In this case, however, such arc tubes need to have end portionsat which electrodes are attached wound around a predetermined verticalaxis.

The end portions of the arc tube may be wound around a predeterminedvertical axis (the spiral axis in the above embodiments) in such amanner that the end portion is viewed in an arch-shape from above in thedirection of the vertical axis) and is viewed in an L-shaped from sidein the direction perpendicular to the vertical axis (in the case wherethe spiral angle is 90°). In this case, the insertion-guiding units (andthe covering units) of the holding member need to be formed in thedirection perpendicular to the above vertical axis. Alternatively,insertion-guiding units may be formed at the bottom wall in such amanner that the end portions of the arc tube come in contact, at onlyside and bottom surfaces thereof, with the insertion-guiding units. Inthis case, too, the ends of the arc tube can be guided to the insertionopenings by rotating the arc tube around the vertical axis.

Further, only one of the end portions of the arc tube may be woundaround the spiral axis. In this case, the same effects as produced inthe above embodiment can be produced by the holding member having theinsertion-guiding unit guiding the one end portion when the arc tube isrotated around the spiral axis. The end portion of the arc tube referredto herein is such that its length from the end of the arc tube is atleast equal to the length of the insertion-guiding unit of the holdingmember in the spiral direction.

3. Globe

Although the above embodiments describe the case where the compactself-ballasted fluorescent lamp does not have a globe covering the arctube, the present invention can be applied to a compact self-ballastedfluorescent lamp that has a globe.

4. Attachment Processes

The above embodiments describe the case where the holding member isfixed and the arc tube is moved, in the processes of attaching the arctube to the holding member. To be specific, the arc tube is first movedin the spiral-axis direction and then rotated around the spiral axis,without moving the holding member. However, the attachment processes maybe such that the arc tube is fixed and the holding member is moved, orboth the arc tube and the holding member are moved. In either case, thesame effects as produced in the above embodiments can be produced.

5. Others

Although the above embodiments describe the case where the presentinvention is applied to a compact self-ballasted fluorescent lampalternative to a 60 W incandescent lamp, the present invention can beapplied to other compact self-ballasted fluorescent lamps such as thosealternative to a 40 W incandescent lamp and a 100 W incandescent lamp.

6. Low-pressure Mercury Lamp

Although the above embodiments describe the case where the presentinvention is applied to a compact self-ballasted fluorescent lamp, thepresent invention can be applied to other lamps such as a compactfluorescent lamp shown in FIG. 16.

The fluorescent lamp 500 includes an arc tube 510, a holder 530, a case540, a globe 550, and a single base 560 (e.g., a GX10q type base). Thearc tube 510 has a double-spiral structure in which a glass tube 520 iswound from its middle to its ends. The holder 530 has a closed one endand is in a cylindrical shape. The holder 530 holds the arc tube 510(specifically, end portions of the glass tube 520). The case 540 isattached at a peripheral wall of the holding member 530. The globe 550covers the arc tube 510. The single base 560 is attached to a socket ofa lighting fixture, and is supplied with power.

The fluorescent lamp 500 greatly differs from the compact self-ballastedfluorescent lamp 1 described in the above embodiments, in that anelectronic ballast is not placed in an internal space formed by theholding member 530 and the case 540 and the base 560 is not of a screwtype, which is the type of bases typically used for incandescent lamps.

As in the above embodiments, the holder 530 has insertion openings,guide grooves, and covering units formed at its bottom wall. With thisconstruction, the arc tube 520 can be easily inserted into the holder530 as in the above embodiments.

INDUSTRIAL APPLICATION

The present invention applicable to a low-pressure mercury lamp can beutilized for enabling ends of an arc tube to be easily inserted into aholding member.

1. A low-pressure mercury lamp, comprising: an arc tube whose at least one end is wound around an axis entirely in a longitudinal direction thereof; and a holding member that holds the arc tube in a state where the at least one end is inserted in an opening formed in a bottom wall of the holding member, wherein the holding member includes a groove that is at a position corresponding to a position of the at least one end and is continuous to the opening, and the groove is formed such that the at least one end of the arc tube wound around the axis fits therein and a depth thereof increases as a distance from the opening decreases.
 2. The low-pressure mercury lamp of claim 1, wherein the insertion-guiding unit is formed as a groove extending in a direction in which the end of the arc tube is wound around the axis.
 3. The low-pressure mercury lamp of claim 2, wherein a part of the groove that comes in contact with a part of the end of the arc tube has a shape corresponding to a shape of the part of the end of the arc tube.
 4. The low-pressure mercury lamp of claim 1, wherein the arc tube includes a pair of lead wires for an electrode extending from the end of the arc tube, the opening opens toward a direction of the axis, and the holding member allows the pair of lead wires to be inserted in the opening.
 5. The low-pressure mercury lamp of claim 4, wherein the opening is formed at an angle of 20 to 60° inclusive with respect to the axis.
 6. The low-pressure mercury lamp of claim 4, wherein the holding member includes a covering unit that is formed so that the opening is positioned at an edge of the covering unit, the covering unit covering the end of the arc tube, and the opening is partially formed by a notch created in the covering unit and/or the insertion-guiding unit.
 7. The low-pressure mercury lamp of claim 1, wherein the end of the arc tube is bonded within the holding member via a bonding agent.
 8. The low-pressure mercury lamp of claim 7, wherein the insertion-guiding unit includes one or more inlets for injecting the bonding agent in an area between (a) the end of the arc tube placed in the holding member and (b) the insertion-guiding unit of the holding member.
 9. The low-pressure mercury lamp of claim 7, wherein the holding member includes a wall at an internal surface thereof for preventing the bonding agent from flowing outside.
 10. The low-pressure mercury lamp of claim 1, wherein the arc tube includes a pair of lead wires for an electrode extending from the end of the arc tube, and the holding member includes a supporting unit for supporting the pair of lead wires while keeping a certain distance between the lead wires.
 11. The low-pressure mercury lamp of claim 1, wherein the arc tube includes a glass tube that is turned at a substantially middle thereof and wound around the axis from the middle, to have a double-spiral structure.
 12. In a lamp having a helical arc tube wound around an axis with a first and second end portion of the arc tube supporting lead wires for electrodes that extend from the respective first and second end portions, the improvement comprising: a holder having a bottom wall with integral first and second covering units extending above the bottom wall and a first and second groove of a configuration to receive and support a rotational movement of the first and second end portions of the arc tube, the first and second grooves are integrally recessed into the bottom wall at predetermined curved distances from the first and second covering units and progressively increase in depth as the first and second grooves curve and extend beneath the respective first and second covering units, the first and second covering units form with the first and second grooves insertion openings of a dimension to approximate a diameter of the arc tube end portions wherein the helical arc tube first and second end portions are inserted into the corresponding first and second grooves and rotated to follow the grooves and enters insertion openings in the first and second covering units for mounting the helical arc tube in the holder.
 13. The lamp of claim 12 wherein the first and second grooves have respective openings through the bottom wall that extend from the insertion opening into and beneath the respective first and second covering units, wherein the lead wires can be initially inserted into the groove openings and the end portions of the arc tubes can subsequently be inserted into the grooves and rotated into the insertion openings.
 14. The lamp of claim 12 wherein the holder further includes a supporting unit for supporting the lead wires positioned to receive and separate the lead wires beneath the insertion openings, the supporting unit formed integral with the holder. 